Funding Your Wallet on Base
The AgentBureau API charges in USDC on Base (Chain ID 8453 mainnet, 84532 Sepolia testnet). USDC on Ethereum L1, Polygon, Arbitrum, Optimism, or sitting on a CEX does not count — the smart contract on Base cannot see balances on other chains. If your transfer reverts with ERC20: transfer amount exceeds balance, that is almost always why.
You need two things on Base:
- At least the USDC fee for the endpoint (e.g. 1 USDC for
/v1/fax). - A small amount of ETH for gas — ~$0.50 is plenty for ~50 transactions; a USDC transfer on Base costs less than $0.01.
Easiest: withdraw from Coinbase
Section titled “Easiest: withdraw from Coinbase”If you hold USDC on Coinbase, withdraw it directly to Base — it’s free and instant.
- Coinbase → Send/Receive → Send USDC.
- Paste your wallet address.
- Network: select “Base” (not “Ethereum”). This is the critical step.
- Send.
- Repeat for a tiny amount of ETH (also pick “Base” as the network).
From Ethereum L1
Section titled “From Ethereum L1”Use the official Base bridge: https://bridge.base.org.
- Connect the wallet that holds your USDC/ETH.
- Bridge
Ethereum → Base. - Pick the asset (USDC or ETH), amount, and confirm. Costs L1 gas (~$2–5) and takes ~10 minutes.
The bridged USDC arrives as native USDC at 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 — the same contract the API expects.
Watch out for
USDbC. Base also has a legacy bridged token called USDbC at0xd9aaEc86B65D86f6A7B5B1b0c42FFA531710b6Ca. It is not the same asset. The API only accepts native USDC.
From another L2 (Arbitrum, Optimism, Polygon, …)
Section titled “From another L2 (Arbitrum, Optimism, Polygon, …)”Cross-rollup bridges are faster than going via L1:
- https://app.across.to — fast, cheap, supports USDC and ETH.
- https://www.relay.link — similar.
- https://app.squidrouter.com — broader chain coverage.
Pick your source chain → destination “Base” → asset → confirm.
Testnet (Base Sepolia)
Section titled “Testnet (Base Sepolia)”For the playground’s testnet mode, use the Circle faucet:
- USDC: https://faucet.circle.com (pick “Base Sepolia”).
- Sepolia ETH for gas: https://www.alchemy.com/faucets/base-sepolia or https://www.coinbase.com/faucets/base-ethereum-sepolia-faucet.
Verify your balance
Section titled “Verify your balance”Before retrying the playground, confirm the funds landed:
https://basescan.org/token/0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913?a=YOUR_ADDRESSIf that page shows ≥ 1 USDC for your connected wallet, you’re ready to go.